Fundamental heat transfer physics of rotating heat exchangers and practical realization of non-vapor compression refrigeration.
Abstract not provided.
Staats, JR, Wayne Lawrence↗
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Results for “non-vapor compression”
Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Field Demonstration and Adoption Impacts of an Affordable Thermoelectric Heat Pump
This study presents the design, field validation, and utility impacts of an air source heat pump that uses thermoelectric (TE) technology to provide supplemental heating at outside air temperatures below 17°F. Conventional heat pumps experience reduced heating capacity and COP at low outdoor temperatures due to the temperature difference between the source and demand sides of the vapor compression cycle. Consequently, during colder months, supplemental heating such as electric resistance or natural gas furnace is often needed to provide additional warmth, which increases the overall equipment and energy costs. To address this challenge, a TE subcooler (an array of solid-state, thermoelectric modules that provides heat pumping using non-vapor compression technique) is fabricated and integrated with the vapor compression cycle of a conventional air-source heat pump. In colder ambient conditions, TE subcooler exchanges heat with the refrigerant to provide additional subcooling, thereby enhancing the capacity of the heat pump. The operation of thermoelectric-integrated heat pump was demonstrated in an occupied single-family home in Nashville, TN. The TE subcooler increased the system’s heating capacity at 15°F outdoor temperature by 25–30% and reduced electricity demand by 10%. It also met the heating load in the house without supplemental electric resistance down to 5°F outdoors, delivering the additional heat at nearly 80% greater efficiency compared to electric resistance heating. With a modest first cost increment of 10–15% over conventional single-speed heat pumps, this approach offers a promising, energy-efficient solution to accelerate residential heat pump adoption in the U.S.
KRISHNAMOORTHY, Sreenidhi [Electric Power Research↗
Materials research and development needs to enable efficient and electrified buildings
Because of the complexity of modern buildings—with many interconnected materials, components, and systems—fully electrifying buildings will require targeted R&D and efficient coordination across those material, component, and system levels. Because buildings that consume the smallest amount of energy are easier to electrify, energy efficiency is a crucial step toward fully electrified buildings. Materials advances will play an important role in both reducing the energy intensity of buildings and electrifying their remaining energy use. Materials are currently being explored, discovered, synthesized, evaluated, optimized, and implemented across many building components, including solid-state lighting; dynamic windows and opaque envelopes; cold climate heat pumps; thermal energy storage; heating, ventilating, and air conditioning (HVAC); refrigeration; non-vapor compression HVAC; and more. In this article, we review the current state-of-the-art of materials for various buildings end uses and discuss R&D challenges and opportunities for both efficiency and electrification.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
Effect of Composition on the Phase Structure and Magnetic Properties of Ball-Milled LaFe11.71-xMnxSi1.29H1.6 Magnetocaloric Powders
Magnetocaloric alloys are an important class of materials that enable non-vapor compression cycles. One promising candidate for magnetocaloric systems is LaFeMnSi, thanks to a combination of factors including low-cost constituents and a useful curie temperature, although control of the constituents’ phase distribution can be challenging. In this paper, the effects of composition and high energy ball milling on the particle morphology and phase stability of LaFe11.71-xMnxSi1.29H1.6 magnetocaloric powders were investigated. The powders were characterized with optical microscopy, dynamic light scattering, X-ray diffraction (XRD), and differential scanning calorimetry (DSC). It was found that the powders retained most of their original magnetocaloric phase during milling, although milling reduced the degree of crystallinity in the powder. Furthermore, some oxide phases (<1 weight percent) were present in the as-received and milled powders, which indicates that no significant contamination of the powders occurred during milling. Finally, the results indicated that the Curie temperature drops as Fe content decreases (Mn content increases). In all of the powders, milling led to an increase in the Curie temperature of ~3–6 °C.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Experimental Investigation of the Effect of Atomizing Electrospray Nozzles on the Cooling and Reduced Humidification of Air
Separating sensible and latent cooling have shown the potential to reduce energy consumption in A/C systems for building HVAC applications. Several technologies exist based on vapor-compression refrigeration, enthalpy wheels, chemical adsorption and absorption materials, and mechanical cooling. However, their thermodynamics limits and high energy consumption hinder their deployment in hot and humid climatic regions. This paper focuses on separating sensible and latent cooling by using a new thermodynamics process and in-kind (i.e., non-vapor compression-based) technology. Highly electrically charged water droplets were sprayed in the airflow. These droplets attracted water vapor molecules to their surfaces and promoted condensation. The phenomenon was the result of simultaneous dielectrophoresis and electro-diffusion interactions. Studies in the literature have shown that using multiple capillary electrodes reduced air moisture by up to 5% when using nanometer-size droplets in the spray. Unfortunately, these studies were limited to low airflow rates, and the objective of this paper was to investigate how to scale up this in-kind approach to airflows typical of buildings. In the present paper, droplets of micrometer size were utilized to control the humidity for a 5-cfm flow rate. While this airflow was still low for building applications, it was 100 times fold the airflows in the literature studies. The air was tested at 20°C and at 50 and 80% relative humidity. A two-fluid atomizing nozzle produced the droplets in the spray, and high DC electric potential, up to 25 kV, was used to charge the fine droplets electrically. The air atomizing nozzle with high voltage potential resembled an evaporative cooler process. However, a measurable reduction of the absolute humidity of up to 2% was observed compared to the case of the nozzle with no high voltage potential. The entire device had one small nozzle selected from off-the-shelf components and had less than a 9 cm2 footprint area.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
High-Efficiency Solid State Heat Pump Module
The baseline heat pumping technology today is dominated by vapor compression refrigeration cycle that involves use of global warming potential fluids (e.g. hydrofluorocarbons HFC). Current regulations (e.g. 2016 Kigali agreement) and market needs are driving HVAC&R related building, automotive and aerospace industries to safe, compact and cost-effective systems with low global warming potential (GWP) footprint (i.e. direct GWP impact) and higher efficiencies (i.e. indirect GWP impact) and low life cycle cost. Among the solid-state technology options, electrocaloric heat pumping (ECHP) technology has potential to be more efficient, quiet and compact than vapor compression systems. However, electrocaloric technology is still at low maturity, as expressed by standard technology readiness level (TRL) assessments and hence was the focus of the current effort. During the current research effort, UTRC proved feasibility (TRL2/3) of the direct-air ECHP concept by demonstrating cooling of ambient air by 8.4°C (under no load conditions) in a laboratory environment. To the team’s knowledge this is the largest direct air cooling demonstration using electrocaloric technology. The technology was matured from lab-scale dime-sized materials to module-scale dimensions and further demonstrated the feasibility of integrating these electrocaloric materials into modules for providing direct-air cooling. The use of inexpensive polymer-based materials validates the economic feasibility of the proposed technology. Future effort is required to further mature this promising technology to TRL 4/5 demonstrating module and system performance at full capacity and efficiency. Maturity to beyond TRL4/5 could be done with limited potential field trials. Successful field trials can pave the way for commercialization. At full commercialization, electrocaloric based heating and cooling technologies have the potential to enable annual energy savings upwards of a quadrillion BTUs and reduction of 10s of million metric tons/yr of Green-House Gas (GHG) emissions in the US, leapfrogging emerging technologies and disrupting traditional cooling and heating systems in residential and commercial HVAC applications and enabling new applications. This would result in reduction of energy imports, greenhouse gas (GHG) emissions and help create US jobs in this new technical area.
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
ThermoLift – A Natural Gas Fired Air Conditioner and Heat Pump
ThermoLift is developing TC-Cycle™, a natural-gas driven air conditioner and cold-climate heat pump that can provide space heating, water heating, and air conditioning in a single device. Unlike traditional heat-pump system, the TC-Cycle system uses helium as working fluid in place of high global warming potential HFC refrigerant. The system has broad application as a combined HVAC solution and technology development throughout this program has advanced the Technology Readiness Level (TRL) from TRL-1 to TRL-5 achieved in the Gen 3.0 prototype. In August of 2013, the US Department of Energy (DOE) provided Research and Development funding through the Building Technologies Innovations Program Funding Opportunity Announcement DE-FOA-0000823. The statement of work (SOW) outlined a deliverable of testing at ORNL and a final test report prepared to include various heating cooling temperature ranges and performance analysis. Furthermore, a milestone of this effort was to analyze all test data to establish further efficiency improvements and consider optimum manufacturing methodologies to facilitate the next level improvements. ThermoLift’s Gen 3.0 gas-fired heat pump was shipped and installed into ORNL’s test facility with most of the data reported herein obtained on August 6, 2018. Uninterrupted operation demonstrated cycle Coefficient of Performance (COP) well exceeding DOE targets for cold-climate heat pumps. Furthermore, there was no degradation in capacity as inlet (ambient) temperature decreased.
03 NATURAL GAS↗